Chemistry

Designer Bindings

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Science  10 May 2002:
Vol. 296, Issue 5570, pp. 985
DOI: 10.1126/science.296.5570.985c

Multidentate ligands are organic molecules that display several functional groups, such as C=O groups, that can be used to bind, or chelate, a transition metal ion. Many “off-the-shelf” ligands commonly used in inorganic chemistry are not actually optimized for chelation and must twist considerably during binding, which weakens the overall interaction.

Lumetta et al. examined theoretically the interaction of some commonly used ligands for binding actinide and lanthanide ions, the alklyated malonamides. They then designed a bi-cyclic variant in which the C=O groups are oriented in both the cis and trans conformers so that they favor a lower energy structure that undergoes little reorganization upon binding. In acidic media, this ligand showed an improvement of seven orders of magnitude improvement in the binding constant for Eu3+ as compared with several noncyclic malonamides.—PDS

J. Am. Chem. Soc. 10.1021/ja025854t (2002).

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